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Biomedical subjects

S Hamilton

Publications and source records attributed to S Hamilton.

17 recordsLinked to original sources
PubMed1992

Serum antibodies to L-type calcium channels in patients with amyotrophic lateral sclerosis.

BACKGROUND AND METHODS: Sporadic amyotrophic lateral sclerosis is a chronic, progressive degenerative disease of the motor neurons of the spinal cord and motor cortex. The cause is unknown. Recent electrophysiologic studies in animals indicate that immunoglobulins from patients with this disease alter presynaptic voltage-dependent calcium currents and calcium-dependent release of neurotransmitters. To determine whether similar interactions might be identified biochemically, we used an enzyme-linked immunosorbent assay (ELISA) to detect the reaction of serum IgG with purified complexes of L-type voltage-gated calcium channels from rabbit skeletal muscle. The results from patients with amyotrophic lateral sclerosis were compared with those obtained from patients with other types of motor neuron disease, patients with autoimmune and non-autoimmune neurologic diseases, and normal subjects. RESULTS: Serum samples from 36 of 48 patients with sporadic amyotrophic lateral sclerosis (75 percent) contained IgG that reacted with L-type calcium-channel protein, and serum reactivity on ELISA correlated with the rate of disease progression (Spearman rank-correlation coefficient, 0.62). Reactive serum was present in only 1 of 25 normal subjects and 1 of 35 control patients with no motor neuron disease. Antibodies to L-type voltage-gated calcium channels were identified in 6 of 9 patients with Lambert-Eaton syndrome, and in 3 of 15 patients with Guillain-Barré syndrome. CONCLUSIONS: Antibodies to L-type voltage-gated calcium channels are present in the serum of patients with amyotrophic lateral sclerosis, and antibody titers correlate with the rate of disease progression. Together with previous data, these results suggest a role for autoimmune mechanisms in the pathogenesis of sporadic amyotrophic lateral sclerosis.

Amyotrophic Lateral Sclerosis↗
PubMed1992

Evaluation of an automated immunodiagnostic assay system for direct detection of herpes simplex virus antigen in clinical specimens.

The Vitek ImmunoDiagnostic Assay System (VIDAS) is a 2 1/3-h automated qualitative enzyme-linked fluorescent immunoassay developed for the direct detection of herpes simplex virus (HSV) antigen in clinical specimens. A total of 356 clinical specimens submitted for HSV isolation were prospectively evaluated with the VIDAS, and the results of the technique were compared with those of both HSV isolation in cell culture and Herpchek, a nonautomated enzyme immunoassay. Compared to cell culture, VIDAS had a sensitivity of 91.6% and a specificity of 89.3%, with positive and negative predictive values of 82.6 and 95.0%, respectively. In comparison to Herpchek, VIDAS had a sensitivity of 93.7% and a specificity of 93.0%, with positive and negative predictive values of 89.4 and 95.9%, respectively. The results demonstrated that the VIDAS required minimal manipulation in order to produce results comparable to those of Herpchek and HSV isolation in cell culture.

Antigens, Viral↗
PubMed1979

Radio-isotope bone scanning in suspected osteomyelitis in children.

The usefulness of radio-isotope bone scanning in suspected osteomyelitis has been widely acclaimed. Fourteen children had rectilinear bone scans performed three hours after injection of Tc99m methylene diphosphonate. A diagnostic accuracy of 56% was achieved, which is lower than in other series. The reasons for this are discussed and the value of bone scanning in the evaluation of osteomyelitis is questioned.

Adolescent↗
PubMed1979

Interaction of actin with myosin A and heavy meromyosin.

Ca2+ "free" actomyosin suspensions as well as actin heavy meromyosin (HMM) solutions in the presence of Ca2+ showed no contractile response (superprecipitation) and had low steady-state Mg2+-ATPase activity. Under the same experimental conditions both the enzymatic activity increased and contractile response was restored if the solubility of the proteins was depressed by the addition of polyethylene glycol 4000 (PEG-4000). The stability of the enzymatically active actomyosin or actin HMM complexes was 10 times lower in cleared solutions than in the insoluble actomyosin or actin HMM suspensions. It was concluded that soluble actomyosin or actin HMM solutions are inadequate test tube models for studying muscular contraction.

Adenosine Triphosphatases↗
PubMed1978

Halothane, surgery, immunosuppression and artificial pulmonary metastases.

C57B1/6 mice were given intravenous tumor cells on day O. Mice were then given either a brief exposure to halothane anesthesia or given halothane and then underwent a hind limb amputation. Immune testing was done at varying time intervals and correlated with the development of artificial pulmonary metastases. The effects of a single 15 minute exposure to halothane on the immune system are probably short-lived and no effect on cell-mediated cytotoxicity was seen on day 7, nor was an increase in pulmonary metastases observed. However, when anesthesia was combined with surgery, cell-mediated cytotoxicity was impaired and an increase in pulmonary metastases was seen. The use of thiabendazole (TBZ), an nonspecific immunopotentiator, in the perioperative period restored the cell-mediated cytotoxic response and resulted in a significant decrease in pulmonary metastases.

Animals↗
PubMed1978

Psychological test performance and sedation thresholds of elderly dements, depressives and depressives with incipient brain change.

As expected, dements, depressives and patients with a mixed psychopathology were differentiated from one another on the sedation threshold measure and on a number of psychological tests. In depressives responding to treatment significant changes in physiological and psychological measures, which had been reported in an earlier study could not be replicated except for an increase of psychomotor speed. In the present sample of patients there were significant correlations between various psychological measures and between them and the levels of the sedation threshold, suggesting that sedation thresholds and psychological tests measured related cerebral functions. Evidence obtained from the earlier investigations to the effect that cerebral age changes short of those occurring in dementia may facilitate the occurrence of depression in late life was only weakly confirmed by the replication study.

Aged↗
PubMed1977

The effect of cyclandelate in depressed and demented patients: a controlled study in psychogeriatric patients.

In a double-blind clinical trial the effects of the vasodilator drug cyclandelate (in a dose of 1200 mg daily) were studied in a group of patients with depressive illnesses or dementing conditions. The measures used before treatment and after six weeks' treatment were: clinical rating, psychometric tests (Paired Associate Learning Test, Digit Copying Test, Digit Substitution Test, and Serial Learning Test), cortical evoked potentials, the sedation threshold and the Gresham Questionnaire. In the depressive group there were no significant differences in the changes in scores at six weeks in three groups: those who received cyclandelate plus amitriptyline, those who received placebo plus amitriptyline, and those who received neither placebo nor cyclandelate. In the demented group there were significant changes in favour of the placebo on two measures (Digit Copying test, and one component of the auditory evoked response). The results do not support the previously reported views claiming, in a number of studies, a significant improvement in the performance of both demented and normal elderly subjects treated with cyclandelate. The significance of these findings is discussed.

Aged↗
PubMed1977

Cyproheptadine inhibition of stimulated plasma renin activity.

Plasma renin activity (PRA) was stimulated by oral frusemide (60 mg) in 4 normal male subjects. Cyproheptadine (Periactin), a serotonin antagonist, was then administered (2 mg orally four times daily) for 7 days and the PRA response to frusemide re-evaluated in the 4 subjects. A highly significant mean inhibition (P less than 0.01) of frusemide stimulated PRA was demonstrated after cyproheptadine administration. Our results show that serotonin, presumably acting via central pathways, may play a role in renin regulation and that this pathway can be inhibited by cyproheptadine.

Adult↗
PubMed1976

The growth of respiratory syncytial virus in organ cultures of bovine foetal trachea.

Respiratory syncytial (RS) virus grown in organ cultures of bovine foetal trachea at 37 degrees C and pH 7.2 reached maximum titres of up to 1 X 10(5) PFU/ml between 11 and 21 days after inoculation. Virus yield was increased three fold by incubation at 33 degrees C, but depressed by the addition of RS virus antiserum, with or without bovine complement, or by the addition of alveolar macrophages. Variation in pH or the concentration of foetal calf serum and magnesium chloride did not affect the virus yield. Virus growth did not affect ciliary activity of the cultures. Histological changes involved slight flattening of the epithelium and the appearance of phloxinophilic inclusion bodies. Fluorescent antibody staining showed more virus antigen in the peri-tracheal connective tissue than in the ciliated epithelium. The presence of non-cytopathic mucosal disease (MD) virus in RS virus infected organ cultures slightly depressed RS virus growth but did not influence ciliary activity. These in vitro experiments suggest that the tracheal epithelium may not be an important target in the pathogenesis of RS virus infection in vivo.

Animals↗
PubMed1976

Properties of condensed bacteriophage T4 DNA isolated from Escherichia coli infected with bacteriophage T4.

Methods developed for isolating bacterial nucleoids were applied to bacteria infected with phage T4. The replicating pool of T4 DNA was isolated as a particle composed of condensed T4 DNA and certain RNA and protein components of the cell. The particles have a narrow sedimentation profile (weight-average s=2,500S) and have, on average, a T4 DNA content similar to that of the infected cell. Their dimensions observed via electron and fluorescence microscopy are similar to the dimensions of the intracellular DNA pool. The DNA packaging density is less than that of the isolated bacterial nucleoid but appears to be roughly similar to its state in vivo. Host-cell proteins and T4-specific proteins bound to the DNA were characterized by electrophoresis on polyacrylamide gels. The major host proteins are the RNA polymerase subunits and two envelope proteins (molecular weights, 36,000 and 31,000). Other major proteins of the host cell were absent or barely detectable. Single-strand breaks can be introduced into the DNA with gamma radiation or DNase without affecting its sedimentation rate. This and other studies of the effects of intercalated ethidium molecules have suggested that the average superhelical density of the condensed DNA is small. However, these studies also indicated that there may be a few domains in the DNA that become positively supercoiled in the presence of high concentrations of ethidium bromide. In contrast to the Escherichia coli nucleoid, the T4 DNA structure remains condensed after the RNA and protein components have been removed (although there may be slight relaxation in the state of condensation under these conditions).

Bacterial Proteins↗
PubMedDate not supplied

Psychiatric problems of the 1970's.

This paper describes some of the social trends of the 1970's that may be affecting patterns of psychiatric needs and presents data showing their impact. It suggests possible psychiatric and sociopolitical responses to meet these needs. Patients were studied in the outpatient and inpatient services of the Shands Teaching Hospital and Student Mental Health Services at the University of Florida. The main findings were that single youth, both females and especially males, were requiring less help since the winding down of American participation in the Vietnam War, perhaps indicating that youth are feeling less alienated from the national effort. Black women are seeking help more than ever before, probably because the black liberation movement has offered them hope that psychiatry can help them. Despite the women's liberation movement, white women still remain the largest group of psychiatric outpatients, as they were in the 1950's and 1960's.

Adult↗